Computing device using bypass assembly

ABSTRACT

A computing device includes a first connector near a first wall. The first connector is in communication with a chip package positioned apart for the first wall via a first cable. The chip package includes a chip supported by a support layer. The chip can be supported by a substrate and/or a circuit board. A second connector can be positioned near a second wall and can also be in communication with the chip package via a second cable. If desired, the substrate or circuit board can include a signal board connector that is configured to engage board connectors terminated to ends of the first and second cables.

RELATED APPLICATIONS

This application is a national phase of PCT Application No.PCT/US2016/030757, filed May 4, 2016, which is incorporated herein byreference in its entirety and which claims priority to the followingU.S. provisional patent application No. 62/156,602, filed May 4, 2015;U.S. provisional patent application No. 62/156,708, filed May 4, 2015;U.S. provisional patent application No. 62/167,036, filed May 27, 2015;and U.S. provisional patent application No. 62/182,161, filed Jun. 19,2015, all of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

This disclosure relates to field of high frequency signaling, moreparticular to computing systems positioned in a chassis.

DESCRIPTION OF RELATED ART

Computing devices such as routers, servers, switches and the like needto operate at high data transmission speeds in order to serve the risingneed for bandwidth and delivery of streaming audio and video in many enduser devices. These devices include a chassis that supports a circuitboard that in turn supports various circuits and use signal transmissionlines that extend between a primary chip member, such as an applicationspecific integrated circuit (ASIC), field programmable gate array(FPGA), digital signal processor (DSP), etc., mounted on the circuitboard and connectors mounted to the circuit board. These transmissionlines are formed as conductive traces on or in the circuit board andextend between the chip member(s) to external connectors or circuitry ofthe device.

As can be appreciated, the integrated circuits (often referred to aschips) are the heart of these electronic devices. These chips typicallyinclude a processor and this processor has a die that can be connectedto a substrate (its package) by way of conductive solder bumps. Thepackage may include micro-vias or plated through holes which extendthrough the substrate to solder balls. These solder balls can comprise aball grid array by which the package is attached to the circuit board.The circuit board includes numerous traces which designated definetransmission lines that include differential signal pairs, ground pathsassociated with the differential signal pairs, and a variety of lowspeed transmission lines for power, clock signals and other functions.These traces are routed from the ASIC to the I/O connectors of thedevice into which external connectors are connected, as well as othersthat are routed from the ASIC to backplane connectors that permit thedevice to be connected to an overall system such as a network server orthe like, or still others that are routed from the ASIC to componentsand circuitry on the motherboard or another circuit board of the device.

Typical circuit boards are usually formed from an inexpensive materialknown as FR4, which is inexpensive. Although inexpensive, FR4 is knownto be lossy in high speed signal transmission lines which transfer dataat rates of about 6 Gbps and greater (e.g., above 3 GHz signalingfrequencies). These losses increase as the frequency increases andtherefore make FR4 material undesirable for the high speed data transferapplications at signaling frequencies of about 10 GHz and greater. Inorder to use FR4 as a circuit board material for high frequency signaltransmission lines a designer may have to utilize amplifiers andequalizers, which increase the final cost of the device.

The overall length of the signal transmission lines in FR4 circuitboards can exceed threshold lengths, about 10 inches, and may includebends and turns that can create signal reflection and noise problems aswell as additional losses. As noted above, losses can sometimes becorrected by the use of amplifiers, repeaters and equalizers but theseelements also increase the cost of manufacturing the final circuit boardand further complicate the layout of the circuit board. In addition, therouting of signal transmission lines in the circuit board may requiremultiple turns and/or transitions. These turns and the transitions,which occur at termination points along the signal transmission lines,tend to reduce the signal to noise ratio. In addition, transitions andterminations tend to create impedance discontinuities that causereflections in the signals, making it difficult to overcome the signalto noise issue by simply increase the power of the transmission. As aresult, the use of a circuit board, especially with the use of FR4 buteven with the use of more costly materials, to route signals overdistance becomes increasingly difficult as data rates increase.Consequentially, certain individuals would appreciate furtherimprovements.

SUMMARY

A bypass assembly is used to provide a high speed data transmission lineextending between a device chip or chip set and backplanes or circuitboards. The bypass cable assemblies include cables which contain signaltransmission lines that can avoid, or bypass, a supporting circuitboard, no matter the material of construction.

In such applications, an integrated circuit having the form of a chip,such as an application specific integrated circuit (ASIC) or fieldprogrammable gate array (FPGA), is provided as part of an overall chippackage. The chip can be mounted on a package substrate by way ofconventional solder bumps or the like and may be enclosed within andintegrated to the substrate by way of an encapsulating material thatoverlies the chip and a portion of the substrate. The package substratecan include traces or leads that extend from the solder bumps on thechip bottom to a termination area on the substrate. The substrate canfurther support a connector or contact pads or can alternatively bemounted on a circuit board that includes traces that couplecommunication points on the substrate to contact pads on the circuitboard. A first connector can then be mounted on the circuit board forinterfacing with a cable assembly. If desired, the first connector canbe mateable with a second connector. Cables, which are terminated toeither the first connector or the second connector, extend to externalinterfaces, such as I/O connectors and backplane connectors.

The chip package may include a plurality of contacts in the form ofsolder balls disposed on the underside of a chip package for providingconnections to and from logic, clock, power and low-speed and high speedsignal circuits to traces on the motherboard of a device in which thechip package is used. If the substrate directly supports a connectinginterface then the contacts associated with the high speed signalcircuits of the chip are removed from the bottom of the chip packageinasmuch as the high speed traces are no longer routed to the bottom ofthe chip package. However, if the substrate is mounted on a circuithoard then high speed traces may be routed to the circuit board andextend some short distance to an appropriate connector.

Cables utilized for such assemblies can be designed for differentialsignal transmission and preferably are twin-ax style cables that utilizepairs of signal conductors encased within dielectric coverings to formtwo wires, or a signal wire pair. First ends of the wire pairs aretypically terminated to corresponding chip packages and second endsthese wire pairs are terminated directly to terminals of entry or exitconnectors, such as I/O and backplane connectors.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not limitedin the accompanying figures in which like reference numerals indicatesimilar elements and in which:

FIG. 1 is a perspective view of an electronic device, such as a switch,router or the like with its top cover removed, and illustrating thegeneral layout of the device components and a bypass cable assembly inplace therein;

FIG. 2 is the same view as FIG. 1, with the bypass assembly removed fromwithin the device for clarity;

FIG. 2A is a perspective view of only the bypass assembly of FIG. 2;

FIG. 2B is the same as FIG. 2A, but with the chip package substrateand/or encapsulant removed for clarity;

FIG. 2C is an enlarged detail view of the termination area surroundingone chip used in the bypass assembly of FIG. 1;

FIG. 2D is a perspective view of the end of a twin-ax cable used in thebypass assemblies;

FIG. 3A is a schematic cross-sectional view of a known structuretraditionally used to connect a chip package to a motherboard in anelectronic device such as a router, switch or the like, by way of tracesrouted through or on the motherboard;

FIG. 3B is a schematic cross-sectional view, similar to FIG. 1A, butillustrating the structure of bypass assemblies such as that illustratedin FIG. 1, which are used to connect a chip package to connectors orother connectors of the device of FIG. 1, utilizing cables andconsequently eliminating the use of conductive traces as signaltransmission lines on the motherboard as illustrated in the device ofFIG. 1;

FIG. 4 is a perspective view of a cable-direct connector assemblyconstructed in accordance with the principles;

FIG. 4A is a sectional view of the connector assembly of FIG. 4, takenalong lines A-A thereof;

FIG. 5 is an exploded view of a cage and the cable-direct connectorassembly of FIG. 4;

FIG. 5A is the same as FIG. 5, but with the receptacle connector inplace within the cage and the bottom fixed to the sidewalls of the cage;

FIG. 6 is a perspective view taken from the bottom, of the cage of FIG.5, with the bottom wall removed and the connector assembly removed outfrom inside of the cage;

FIG. 6A is the same view as FIG. 6, but with the connector assembly inplace within the cage;

FIG. 6B is the same view as FIG. 6A, but with the bottom wall in placeto seal the cable direct connector assembly in the cage;

FIG. 7 is a partially exploded view of the connector assembly of FIG. 4;

FIG. 8 is a more fully exploded view of the connector assembly of FIG.7;

FIG. 8A is an exploded view of one terminal array of the connectorassembly, its associated ground plates and a set of corresponding cablesand wires used in the connector assembly of FIG. 4;

FIG. 8B is the same view as FIG. 8A, but illustrating the componentsthereof in an assembled state to form a basic connector element;

FIG. 8C is a perspective view of two basic connector elements assembledtogether to form a receptacle connector terminal array;

FIG. 8D is an enlarged detail view of two of the cables in a connectorelement, illustrating the elevated ground plate structure utilizedtherewith;

FIG. 9 is a front elevational view of the cage illustrating a portion ofan edge card contacting the terminal contact portions of the connectorassembly;

FIG. 10 is an enlarged detail view, of the bottom of the rear end of acage with the connector assembly in place;

FIG. 11 is a perspective view of a cage which is utilized in the bypassassemblies thereof;

FIG. 11A is a sectional view of the connector of FIG. 11, taken alonglines A-A thereof;

FIG. 11B is a side elevational view of FIG. 11A;

FIG. 12 is a perspective view of the connector of FIG. 11; but takenfrom the rear of the opposite side;

FIG. 13 is a bottom plan view of the connector of FIG. 6A, with thebottom removed for clarity;

FIG. 13A is a sectional view of an empty cage without the internalconnector and heat transfer member in place;

FIG. 14 is a top plan view of the cage with the top wall removed fromthe cage and a portion of an edge card engaged with the internalconnector;

FIG. 14A is the same view as FIG. 14, but sectioned at a level beneaththe rear cover plate to illustrate the internal connector and the mannerin which it engages the body of the cage;

FIG. 14B is a vertical sectional view taken through the cage proximateto the front of the internal connector, with a portion of the internalcage removed for clarity to illustrate the hollow interior space of thecage and the internal ribs thereof which contact the connector elementsand hold an EMI absorbing pad in place thereof;

FIG. 15 is a perspective view of a pair of cages with heat transfermembers and indicator lights arranged in a vertical stack on a circuitboard;

FIG. 15A is an exploded view of FIG. 15;

FIG. 16 is a perspective view of three cages arranged vertically in ahorizontal row on face plates of a device;

FIG. 16A is an exploded view of a vertical cage and face plate mountingassembly:

FIG. 17 is a perspective view of a cage with an improved heat sinkassembly constructed in accordance with the principles attached thereto;

FIG. 18 is a partially exploded view of the cage-heat sink assembly ofFIG. 17, with the heat sink assembly components removed from theirengagement with the top of the cage for clarity;

FIG. 18A is a side view of the exploded view of FIG. 18, with thecomponents depicted therein sectioned along lines C-C thereof;

FIG. 19 is a front elevational view of the cage-heat sink assembly ofFIG. 17, taken along lines 3-3 thereof;

FIG. 19A is a side elevational of the cage-heat sink assembly of FIG.17, taken along the right side thereof;

FIG. 19B is a top plan view of the cage-heat sink assembly of FIG. 17;

FIG. 19C is a longitudinal sectional view of the cage-heat sink assemblyof FIG. 17, taken along lines C-C thereof;

FIG. 19D is a transverse sectional view taken through the cage-heat sinkassembly in the transfer portion of the heat sink assembly of FIG. 17,taken along lines D-D thereof;

FIG. 19E is the same view as FIG. 19D, but with the heat pipe removedfrom the heat sink assembly for clarity and with an alternateconfiguration of a pair of heat pipes shown in phantom;

FIG. 19F is a transverse sectional view, looking rearwardly, takenthrough the cage-heat sink assembly in the dissipating portion of theheat sink assembly of FIG. 17, taken along lines F-F thereof.

FIG. 19G is a transverse sectional view, looking forwardly, takenthrough the cage-heat sink assembly in the dissipating portion of theheat sink assembly of FIG. 17, taken along lines G-G thereof,illustrating the clearance between the heat-dissipating fins and theconnector wires;

FIG. 20 is a perspective view of an alternative cage construction;

FIG. 21 is a perspective view of an embodiment of a computing device;

FIG. 22 is a perspective view of another embodiment of a computingdevice;

FIG. 23 is an enlarged perspective view of the embodiment depicted inFIG. 22;

FIG. 24 is a simplified perspective view of an embodiment of bipasssystem;

FIG. 25 is a simplified, partially exploded view of an embodiment of abipass system;

FIG. 26 is an elevated side view of a cross sectional of a chip packagemounted on a signal circuit board;

FIG. 27 is a simplified perspective view of an embodiment of a signalcircuit board configuration;

FIG. 28A is a perspective view of an embodiment of a connector systemsuitable for connecting to a signal circuit board;

FIG. 28B is another perspective view of the embodiment depicted in FIG.29A; and

FIG. 29 is a schematic representation of an alternative embodiment of achip package.

DETAILED DESCRIPTION

The detailed description that follows describes exemplary embodimentsand is not intended to be limited to the expressly disclosedcombination(s). Therefore, unless otherwise noted, features disclosedherein may be combined together to form additional combinations thatwere not otherwise shown for purposes of brevity. As such, references toa feature or aspect are intended to describe a feature or aspect of anexample, not to imply that every embodiment thereof must have thedescribed feature or aspect. Furthermore, it should be noted that thedescription illustrates a number of features. While certain featureshave been combined together to illustrate potential system designs,those features may also be used in other combinations not expresslydisclosed. Thus, the depicted combinations are not intended to belimiting, unless otherwise noted.

In the embodiments illustrated in the Figures, representations ofdirections such as up, down, left, right, front and rear, used forexplaining the structure and movement of the various elements, are notabsolute, but relative. These representations are appropriate when theelements are in the position shown in the Figures. If the description ofthe position of the elements changes, however, these representations areto be changed accordingly.

As can be appreciated, the discussion that follows relates to signaltransmission. Signals are often referred to as low speed or high speedby persons of skill in the art, depending on the data rate (low datarates being referred as low speed signals and high data rates beingreferred to as high speed signals). While such nomenclature istechnically not the most precise way to refer to such matters, to beconsistent with typical usage the low speed/high speed convention willalso be used herein.

Embodiments depicted herein are suitable for use with high speed datasignal transmission line systems that support high data rates at lowlosses from chips or processors and the like to backplanes, motherboards and other circuit boards. An assembly is disclosed that connectsthe chip package of a device to entry connectors (which can be used toprovide signals into or out of the device) without significant use oftraces on a circuit board so that reduced losses are possible. Ifdesired, an improved connector for use as an entry connector can beconnected directly to cables or wires, rather than traces on circuitboards, to define signal transmission lines from the connector directlyto chips and processors of the host device. Such a configuration ishelpful for what is considered high speed data applications (above 10Gbps) and above typically will be beneficially utilized in systemsoperating above 15 Gbps if NRZ encoding is being used. Because thereceptacle connectors can be contained entirely within the connectorstructure and do not need to be directly connected to a circuit board,the bottom wall of the cage can be continuous in its extent tocompletely seal off the bottom of the cage and thus can improve EMIperformance of the connector. The use of press-fit pins to mount theconnectors can also be eliminated. Pairs of connector elements in theform of wafers are provided which fit into an opening in the rear of thereceptacle connector. A primary ground plane is provided between theconnector elements to block signal interference, such as crosstalk,between the signal terminals of the two connector elements. Accordingly,the connectors may be mounted individually to a face panel or a wall ofthe host device, or even interconnected with other connectors to form anintegrated assembly of connectors that are suitable for vertical orhorizontal stacking. Furthermore, if desired, the connector can bepositioned within the host device as an internal transition connectorthat can be supported on a circuit board, on standoffs or other supportsor stand alone. This structure defines connectors with high speedconnectors that form signal transmission lines useful for high speeddata applications at 10 Gbps or above that can bypass circuit traces onthe host device circuit board.

The data rates of the devices for which the above-described connectorsis used are quite high (10 Gbps and often 20 Gbps+) and often theconnectors are used with active cable assemblies that tend to generatesubstantial heat during data transmission. The connector may furtherinclude a heat sink assembly that extends into an interior portion ofthe cage and which is configured to make contact with the mating moduleinserted into the cage. The cage includes walls that cooperativelydefine the interior which houses a receptacle connector. Inasmuch asthese cages may often be mounted along a face panel of the host device,a heat sink assembly is provided that includes a transfer portion whichmakes contact with the mating module inserted into the cage, and adissipating portion connected thereto, which is depicted spaced apartfrom the transfer portion in a horizontal direction. In this manner, theheat-dissipating portion beneficially extends rearwardly of the shieldedcage and will include downward facing fins. This structure takesadvantage of the open space behind the cage and may provide a reductionin overall height of the host device, assuming the airflow configurationcan be set up accordingly.

In an embodiment, the terminations to at least one set of the connectorsare configured so that the second ends of the wire pairs are terminatedin a manner and spacing that emulates the ordered geometry of the cableso that crosstalk and other deleterious factors are kept to a minimum atthe connector location. In such a configuration all of the connectorterminals have the same length. The free ends of the signal terminalpairs are arranged in desired spacings and include associated grounds sothat the ground associated with each wire pair may be terminated to acorresponding ground of the connector to define an associated groundthat extends the entire length of the cable and its connector. Thisarrangement will provide shielding, and reduction of cross talk, bydefining a ground plane to which the signal terminals can couple to incommon mode, while pairs of signal terminals can couple together indifferential mode. The termination of the cable wires to the connectorscan be done in a manner such that to the extent possible, a specificdesired geometry of the signal and ground conductors in the cable ismaintained through the termination of the cable to the connector.

A single chip package may be provided that includes an integratedcircuit mounted to a substrate. The substrate has termination areas towhich first ends of a plurality of twin-ax cables are terminated. Thelengths of the cables may vary and will be long enough for some of thecables to be easily and reliably terminated to first external interfacesin the form of a single or multiple I/O style connectors which are partof an external connector of either, or both of the entry and exitconnectors. These connectors may be preferably mounted to a panel of thehost device in a fashion that permits external connectors, such as plugconnectors or pluggable modules to be mated therewith. The assembliesmay have their cables extend between entry connectors of the device andthe chip package formed as an integrated assembly, or they may furtherinclude additional cables that extend between the chip package and exitconnectors of the device. The first ends of the bypass cables may beconfigured so that they may be inserted into connectors on the chippackages so as to have “plug and play” capability. In this manner, theexternal connectors can be inserted into the host device as single organged elements, each containing one or more signal transmissionchannels. The chip package may be supported within the cage of thedevice either solely or by way of standoffs or other similar attachmentsto a low cost, low speed motherboard.

Removing the signal transmission lines from the chip to the externalconnectors off of the motherboard in this manner frees up space on themotherboard which can accommodate additional functional components toprovide added value and function to the device, while maintaining a costthat is lower than a comparable device that utilizes the motherboard forsignal transmission lines. Furthermore, incorporating the signaltransmission lines in the cables of the bypass assembly reduces theamount of power needed to transmit high speed signals from the chippackages to the external connectors, thereby increasing the “green”value of the bypass assembly and reducing the operating cost of devicesthat use such bypass assemblies.

The cables extending between connectors and the chip packages arepreferably of the “twin-ax” style, with two wires in each cable so thata pair of signal conductor are running lengthwise of the wire, enclosedin a dielectric covering. The pairs of wires are preferably terminatedto receptacle connectors at the proximal ends of the cables and at theirdistal ends directly to the chip packages. The receptacle connectors arepreferably contained within a connector structure, such as a cage,adapter frame or the like and cooperate with the connector structure todefine a shielded cage configured to receive an external connector, suchas a pluggable module. The second ends of the cable wires are terminateddirectly to the terminals and grounds of the receptacle connectors, andthe cables are preferable held in wafer-like supports to define terminalrows on opposing sides of card slots of the receptacle connectors. Thecables exit the connector structure through the rear wall thereof.

Turning to the figures, FIG. 1 is a perspective view of a computingdevice 50 such as a switch, router, server or the like, and with thecover of the host device removed. The computing device 50 is governed byone or more processors, or integrated circuits, in the form of a chip 52(which can be one or more discrete chips packaged together) that may bepart of an overall chip package 54. The device 50 has a pair of sidewalls 55 and first and second walls, 56, 57. Connectors 80 (which can bein the form of an input/output or IO connector) are provided in thefirst wall 56 (which can be a front wall) of the host device so thatopposing mating connectors in the form of pluggable modules and the likemay be inserted in order to connect to circuits of the device 50.Backplane connectors 30 may be provided in a second wall 57 (which canbe a back wall) for connecting the device 50 to a larger device, such asa server or the like, including backplanes utilized in such devices. Thedevice 50 includes a power supply 58 and cooling assembly 59 as well asa motherboard 62 with various electronic components thereupon such ascapacitors, switches, smaller chips, etc.

FIG. 3A is a cross-sectional view of a prior art conventional chippackage and motherboard assembly that is used in conventional devices.The chip 52 may be an ASIC or any another type of processor orintegrated circuit, such as a FPGA and may be one or more separateintegrated circuits positioned together. Accordingly, the term chip willbe used herein as a generic term for any suitable integrated circuit. Asshown in FIG. 3A, the chip 52 has contacts on its underside in the formof solder bumps 45 that connect it to associated contact pads of asupporting substrate 47. The substrate 47 typically includes platedthrough-holes, micro-vias or traces 48 that extend through the body ofthe substrate 47 to its underside. These elements 48 connect withcontacts 49 disposed on the underside 47 a of the substrate 47 and thesecontacts 49 typically may take the form of a BGA, PGA or LGA and thelike. The chip 52, solder bumps 45, substrate 47 and contacts 49 allcooperatively define a chip package 52-1. The chip package 52-1 ismated, by way of a socket (not shown) to a motherboard 52-2 made of FR4material and used in a device. The motherboard 62 has a plurality oflengthy conductive traces 52 a-c that extend from the chip packagecontacts 49 through the motherboard to other connectors, components orthe like of the device. For example, a pair of conductive traces 52 a,52 b are required to define differential signal transmission line and athird conductive trace 52 c provides an associated ground that followsthe path of the signal transmission line. Each such signal transmissionline is routed through or on the motherboard and such routing hascertain disadvantages.

FR4 circuit board material becomes increasing lossy and at frequenciesabove 10 Ghz this starts to become problematic. Additionally, turns,bends and crossovers of these signal transmission line traces 52 a-c areusually required to route the transmission line from the chip packagecontacts 49 to connectors or other components mounted on the motherboard52-2. These directional changes in the traces 52 a-c can create signalreflection and noise problems as well as additional losses. Losses cansometimes be corrected by the use of amplifiers, repeaters andequalizers but these elements also increase the cost of manufacturingthe final circuit board 52-2. This complicates the layout of the circuitboard 52-2 because additional board space will be needed to accommodatesuch amplifiers and repeaters and this additional board space may not beavailable in the intended size of the device. Custom materials forcircuit boards are available that reduce such losses, but the prices ofthese materials severely increase the cost of the circuit board and,consequently, the electronic devices in which they are used. Stillfurther, lengthy circuit traces require increased power to drive highspeed signals through them and, as such, they hamper efforts bydesigners to develop “green” (energy-saving) devices.

FIG. 3B is a cross sectional view of the chip package 54 that can beused in the device 50 of FIG. 1. The chip 52 contains high speed, lowspeed, clock, logic, power and other circuits which are connected to thechip package substrate 53. Traces 54-1 of the package 54 lead toassociated contact pads 54-2 arranged in termination areas 54-3, thatare preferably disposed at or proximate to edges 54-4 of the substrate53. The chip package 54 may further include an encapsulant 54-5, such asan epoxy, that fixes the chip 52 in place within the package 54 as anintegrated assembly along with associated cable connectors and othercomponents. The chip package 54, as illustrated, be connected in part,to the motherboard by way of solder bumps 49, but such connections donot need to include high speed signal transmission lines in place on thecircuit board 62. However, as discussed below with respect to FIGS.22-29A, the supporting circuit board can include high speed transmissionlines if they travel a short distance. For example, the traces 52 a-ccould quickly terminate to a connector provided on the circuit board 62just outside an outer edge of the substrate 47.

If cables are to terminate directly to the substrate then the cables 60can be terminated to the package contact pads 54-2 by suitablewire-to-board connectors and the like, and these cables 60 arepreferably of the twin-ax construction with two signal conductors 61surrounded by a dielectric covering 61-1. The cables 60 can also includean associated drain wire 61-2 and an outer shield 61-3 and a finishedinsulative outer jacket 61-4. (FIG. 2D.) The use of one or more drainwires is optional, as is the outer shield (which can be in the form of aconductive wrap, braided shield or the like). In some instances, the twoconductors may be encased in a single dielectric covering. The spacingand orientation of the wires that make up each such wire pair can beeasily controlled in a manner such that the cable provides atransmission line separate and apart from the circuit board, and whichmay extend between a chip, chip set, component and a connector locationon the circuit board or between two locations on the circuit board. Incertain embodiments the ordered geometry of the cables as transmissioncomponents makes it easier to maintain a transmission line withacceptable losses and noise as compared to the difficulties encounteredwith circuit board signal transmission lines.

As noted above, the cables 60 and their signal conductor pairs definehigh speed signal transmission lines that lead from the chip package 54to the first (entry) or second (exit) connectors 80, 30. The orderedgeometry of the cables maintains the signal conductors as pairs in apreselected spacing to control the impedance therethrough. Utilizing thecables as signal transmission lines can eliminate the need to lay downhigh speed signal transmission lines in the form of traces on themotherboard, thereby avoiding high costs of exotic board materials andthe losses associated with cheaper board materials such as FR4.

As illustrated in FIGS. 2-2C, the cables 60 have opposing first andsecond ends 163, 164 that are respectively connected to the chip package54 and the connectors 80 (which could be a first connector) or backplaneconnectors 30 (which could be a second connector) to define high speedsignal transmission lines that bypass the motherboard. The cables 60maintain the ordered geometry of the signal conductors throughout thelengths they traverse to and from the chip via the external interfaces.The ordered geometry of the cables permits the cables to be turned, bentor crossed in their paths without introducing problematic signalreflection or impedance discontinuities into the transmission lineswhich can occur in circuit board signal transmission lines. The cables60 are arranged in first and second sets of cables, with the first cableset extending between the connectors 80 and the chip package 54, and thesecond set of cables extending between the chip package 54 and theconnectors 30 in the second wall 57 of the device. The manner in whichthe signal conductors of the cables 60 may be terminated to the chipsubstrate can vary. As illustrated in FIG. 2C, the cables 60 may beterminated by way of wire-to-board connectors 66, which can mate withcontacts on the chip package substrate 54 (which is cut away forpurposes of illustration). The connectors 66 can also mate to connectorsmounted on a surface of circuit board (such as is depicted in FIGS.22-28). Heat sinks 71 may be attached to surfaces of the chips 52 asshown to dissipate heat, or integrated into the assembly by way of theencapsulant. It should be noted that further details of potentialconstruction configurations are disclosed below with respect to theembodiment depicted in FIGS. 22-28.

The chips, substrate, heat sink and cable connectors 66 may integratedtogether by way of an encapsulant or other support structures that holdsthem together as a single assembly as shown in FIGS. 2-2C. Thisstructure permits a device designer to fully utilize the space availableon the motherboard 62 for additional components and circuit which addvalue to the host device without the need for complex circuit boarddesigns. These integrated assemblies can be inserted into devices bymerely inserting the first and second connectors into respectiveopenings in the front and back walls 374, 57 of the host device 50.Ancillary connectors may be provided for connecting the chip package toother circuits of the device as shown in FIG. 3B. The assemblies mayalso be provided in other forms, such as, for example: 1) without thechip package, but with the chip package substrate; 2) with the chippackage and either the first or second connectors, shown respectively at200 and 201 in FIG. 2A; and, 3) with both the entry and exit connectorsarranged to extend to openings in the front wall of the device, as shownat 202 in FIG. 2. In this manner the assemblies 200, 201 and 202 may beinserted into a basic device to provide the device with itsfunctionality without the need to design such functionality into themotherboard 62 of the hose device 50. Additional details for possibleconstruction will be discussed below.

Turning to FIGS. 4, 7 &. 8, an internal connector 70 is received withineach of the connectors 80 and the internal connector 70 includes a body108 formed of an insulative material that includes a card slot 109 thatopens to the front of the connector 70 and to the entrance 67 of theconnector 80. The card slot 109 is an example of a mating interface andwhile the card slot configuration is preferable, other mating interfaceconfigurations are also suitable. The card slot 109 is positioned abovea polarizing channel 110 formed by legs 110 a, 110 b that support thecard slot 109 off of the bottom wall 68 of the connector 80 and preventincorrectly positioned opposing mating connectors from being insertedinto the card slot 109. The body 108 has a plurality ofterminal-receiving cavities 111 aligned on opposite sides of the cardslot 109 which receive contact portions of cantilevered terminals 115 a,115 b of two connector elements 104 a, 104 b. The connector elements 104a, 104 b support the terminals 115 a, 115 b in respective single rows ofterminals as illustrated in FIGS. 4A and 8C. The two connector elements104 a, 104 b each have wafer-like configurations and can be insertedinto the body 108 from the rear to complete the internal connectorassembly. As depicted, the terminal arrays of each connector element 104a, 104 b are thereby positioned on opposite sides of the card slot 109.

FIG. 8A illustrates the basic construction of a connector element 104that is used in the connectors 70. A plurality of twin-ax cables 60 andregular wires 121 are arranged in an array extending widthwise of theconnector 70. The ends of the wires 121 and cables 60 are stripped toexpose the signal conductors 61 of the cables 60 as well as define freeends 121 a, 120 a of the wires and cables, respectively, for terminatingto corresponding tail portions 116 of the connector terminals 115 a, 115b. (FIG. 4A.) In the embodiment illustrated, pairs of the twin-ax cables60 are located at the outer ends of the array, and the drain wires 61-2of the twin-ax cables 120 are bent simply upwardly and then bent againto lie flat on their associated ground plates 125. The terminals 115 a,115 b are held together in their own spaced apart widthwise array by asupport bar 124. This largely maintains the geometry of the cable in theconnector termination.

The depicted receptacle connector 70 has a structure that promotes thesignal integrity of data signals passing therethrough and which providesan impedance transition from the bypass cable wire pairs and thecircuits of a circuit card of an opposing mating connector. Thistransition is from 85 to 100 ohms within a preselected tolerance leveland is done in stages, or three zones so that the transition occurs in agradual manner from an entry level impedance to a first transitionimpedance and then a second transition impedance and then finally to thefinal or third transition impedance. In this manner, the impedancetransition occurs in a somewhat gradual manner over the entire length ofthe receptacle connector rather than occurring in the tail or thecontact portions of that connector. In embodiments where no impedancetransition is needed the transition can be omitted.

If a transition is provided it can provided by presenting threedifferent dielectric mediums through which the receptacle connectorterminals extend. The first zone medium is preferably a hot meltadhesive in which the impedance rises by about 6 ohms from the incomingimpedance of about 85 ohms, and the second zone medium preferablyincludes LCP (liquid crystal polymer) where the impedance rises by aboutanother 6 ohms, and finally the third zone medium includes air in whichthe impedance rises to about 105 ohms, thereby transition the impedancewith a tolerance level of about 5%. The changes in surrounding mediumare also accompanied by changes in the width of the terminals becomingwider or narrower in different zones. The distances between theterminals and associated ground planes can also contribute to thisselected tuning of the impedance. The transition occurs over the lengthof the connector from the tails to the contact ends to present a gradualincrease over a unit length rather than sole in either the tail or thecontact portions of the terminals.

As depicted, the termination areas of the cables/wires 120, 121 to theterminals 115 a, 115 b are disposed in a nest 130, that extendswidthwise and which is formed from an insulative material having adesired dielectric constant. (FIGS. 8A-8D.) The depicted nest 130 has aU-shaped configuration and it is located adjacent the terminal supportbar 124. In this area, the drain wires 61-2 of the cables 60 can bejoined to ground plates 125 that are positioned above the cables 60 andare spaced vertically apart from and above the terminal tail portions116. The ground plates 125 have a plate body 125 a with at least apartially planar surface which the drain wires 61-2 contact and to whichthe drain wires may be soldered, or otherwise connected.

Contact legs 126 are provided as part of the ground plates 125 in orderto form contact portions 128 of the ground plates 125 that arepreferably attached to the tail portions 116 of ground terminals of theconnector 70. The contact legs 126 are vertically offset so that theground plates 125 are spaced apart from and extend over at least aportion of the termination of the signal conductors to the signalterminal tail portions in the row of terminals associated with acorresponding connector element. As shown in FIGS. 8B-8D, each of theground plates 125 preferably include three legs 126 which contact theground terminals of the connector 70 in a manner such that any twosignal terminal tail portions are flanked by two of the contact legs126. This arrangement permits the spacing of the signal terminals toapproximately match that of the signal conductors of the twin-ax cables60 from an impedance perspective. In this manner, a G-S-S-G pattern ofthe terminals 115 a, 115 b is maintained for the internal connector 70within the two rows of terminals on opposite sides of the card slot 109.

A rectangular frame 132 is provided along the rear of each connectorelement 104 a, 104 b and includes four walls 133 (FIG. 8) joinedtogether around a bottom wall 134 to at least partially define a hollowinterior recess 138. The front and rear walls 133 of the frame 132 areperforated as shown with openings 135 that are configured to accommodatethe twin-ax cables 120 and the low power and logic control wires 121 intheir longitudinal extent through the frame 132. The frame 132 is joinedto the nest 130, along its rear face, by an overmolded portion thatfills the termination area. The frame 132 can be formed of a conductivematerial, such as metal, or may have an outer conductive coating, sothat when in place within the connector 80, the connector elements 104a, 104 b make electrical grounding contact therewith. Thus, the framecan provide a path to ground or other reference plane. The connectorelement frames 132 are positioned adjacent to and rearward of the nest(FIG. 8C) and may be fixed to it as noted below.

The sidewalls 133 of the frame 132 may be slotted as shown with verticalslots 136. These slots 136 will engage the sidewalk 106 a, 106 h of therear opening 106 of the connector 80 and because the frames areconductive, they can also alleviate EMI leakage out of the rear opening106 of the connector 80. The open recess 138 of the connector elementframe 132 through which the cables and wires extend is filled with adielectric material, such as a liquid crystal polymer (“LCP”) that fixesthe cables/wires in place in the recess 138 with respect to theconnector element frames 132 and to the nest, which also receives someof the LCP. In this manner, the wafer-like configuration of theconnector elements 104 a, 104 b is defined and this overall structureprovides a measure of strain relief to the twin-ax cables 60.

The bottoms 134 of the two connector elements 104 a, 104 b abut eachother and may engage each other through a post 140 and hole 141 mannerof engagement as shown in FIG. 6. In this manner, the two connectorelements 104 a, 104 h may be inserted into a rear opening of theconnector body 108 so that the terminal contact portions are alignedwith each other and are received in the terminal-receiving cavities 111of the connector body 108 to form an integrated connector assembly. Asillustrated in FIG. 6, the connector assembly is pressed into the hollowinterior space of the connector 60 from below. An internal ground plane142 is provided in the form of a flat, conductive plate that is locatedbetween the two connecting elements 104 a, 104 b. It extends from therear end of the connector element frame 132 to the forward edge of thenest 130. This ground plane 142 acts as a primary ground plane thatserves to block crosstalk between the signal conductor pairs in oneconnector element and the signal conductor pairs in another connectorelement. The ground plates 125, act as secondary ground plates, orbusses to the signal conductors of the cables 120 and their terminationto the signal terminals 115 a.

The slots 136 on the sides of the connector elements 104 a, 104 b engagethe sides 106 a, 106 b of the connector rear opening 106, while twocatches 144 disposed on opposite exterior sides of the connector body108 are received in corresponding openings 146 in the sidewalls 64 a, 64b of the connector 80. The catches 144 may be oversized so as to deformwhen the connector assembly is inserted into place in the cage 63. Theslots 136 may be rounded in configuration with tips 148 pointinginwardly or at each other, in order to ensure reliable contact with theconnector 80. (FIG. 10.)

The two EMI absorbing pads 102 a, 102 b may be applied to opposingsurfaces of the connector elements 104 a, 104 b of the connectorassembly prior to the connector assembly being pressed into the interior61 of the connector 80 from the bottom. The connector elements arevertically slotted, as previously noted, so they can engage the sides106 a, 106 b of the rear wall opening 106 of the connector and thiscontact provides in cooperation with the EMI-absorbing pads, four-sidedEMI leakage protection around the connector elements. The rear wall ofthe connector 80 and the conductive connector elements 104 a, 104 bcombine to form, in effect, a fifth wall that prevents EMI leakage. Thepads 102 a, 102 b seal off the spaces between the connector elements 104a, 104 b and opposing surfaces of the cage 63. These pads 102 a, 102 boccupy the open spaces above and below the connector elements 104 a,104, which are normally empty in conventional connectors.

The EMI pads 102 a, 102 b are preferably aligned with and positionedabove the areas of the connector elements where the cable wires areterminated to the terminal tails of the internal connector 70. Thebottom pad 102 b is held between the bottom wall 68 and the bottomconnector element 104 b, while the top pad 102 a is held in placebetween the top connector element 104 a and the cage rear cover 90. Thisis accomplished by ribs 103 that are formed on the bottom of the rearcover 90 which extend down into contact with the pad 102 a, asillustrated in FIG. 13B. The connector elements, EMI-absorbing pads arethereby sandwiched between the cage top and bottom walls 66, 68 and thepads 102 a, 102 b help ensure that EMI leakage is reduced along the cagerear wall opening 106.

With the twin-ax cables 60 directly terminated to the terminals of theconnector 70, the connectors 80 are configured for mounting off of acircuit board and onto a panel or in a manner so as to be afree-standing connector within a host device. The connectors 80 need notbe mounted to a circuit board 62 in a termination manner, but can be byway of fasteners extending through openings in the circuit board andinto the screw bosses. Thus, the beneficial sealing off of the bottom ofthe connector and elimination of the need for a right-angle connectornot only eliminates the need to mount the connector on the motherboard62, but also facilitates stacking of the connectors in both vertical andhorizontal arrangements.

Accordingly, the wires of the connector may be directly connected tocomponents of the host device, such as a processor or a chip package andthe like bypassing the traces on the circuit board. As the connectionnow may be direct, the connector does not have to be mounted on acircuit board but may be enclosed within a structure such as theconnectors 80 disclosed and be panel mounted. The connectors 80 may bearranged on an adapter frame, which can be configured similar to a cageif desired. Still further, the connector may be used an as internalconnecting sleeve to provide an internal connector that is positionedwithin the host device and which receives a plug-style connector. Theconnector cables are terminated to the connector element terminal tailsat one ends of the cables so the cables can be terminated at theirsecond ends to the chip packages or processors of the host device. Anintegrated bypass assembly such as this can be installed and removed orreplaced as a unit, which bypasses the circuit board and the associatedloss problems which occur in FR4 materials, thereby simplifying thedesign and reducing the cost of the circuit board.

Turning now to FIGS. 4-9, a connector 80 is illustrated in FIGS. 5 and5A that can be used as an external interface that accommodates entryconnectors of the host device. The connector 80 is disposed in the firstwall 374 of the device 50 and receives opposing mating connectors in theform of plug connectors, such as pluggable electronic modules and thelike. The connector 80 includes a cage 63 that is conductive andincludes two sidewalls 64 a, 64 b, a rear wall 65 and top and bottomwalls 66 and 68. All of the walls cooperatively define a hollow interior61 that receives a corresponding opposing external mating connector thatmates with an internal connector 70 so as to define a port. The walls ofthe connector 80 may be formed together as one piece as in an adapterframe, or they may be utilize separate elements that are joined togetherto form an integrated assembly. It should be noted that the connector 80is not limited in its operation to accommodating only pluggable modulesbut can, with the appropriate configuration, accommodate any suitableconnector.

The cage walls 64-66 & 68 are all conductive and provide shielding forconnections made within the connector 80. In this regard, the connector80 is provided with a conductive bottom wall 68 that completely sealsoff the bottom of the cage 63 in contrast to known cages and frames thatare open at their bottoms to the circuit board upon which they aremounted. The depicted connector 80 contains an internal, cable-directconnector 70 (FIG. 4) that has direct wire connections made to itsterminals 115 a, 115 b and therefore does not require termination totraces on the motherboard 62 of the host device 50. Prior art connectorsenclosed by cages or frames are of the right angle type, meaning theconnector extends at a right angle from its mating face to the circuitboard and the traces to which the connector is terminated. Right angleconnector terminations to circuit boards can create signal integrityproblems in high speed operation, due to the varying lengths of theterminals and the bending thereof, such as increased capacitance in thecorners of the bends and jumps or dips in the characteristic impedanceof the system at the connector and its interface with the circuit board.In addition, the exiting of the cables out of the rear of the cage canpotentially eliminate the need to use press-fit pins as a means to mountthe connector to the circuit board, as ordinary mounting holes can beused for threaded fasteners, thereby simplifying the overall design of ahost device motherboard. As depicted, the internal connectors 70 areterminated to wires of cables 60 and exit out of the rear wall 65 of theconnector 80, thereby avoiding the aforementioned problems.

The bottom wall 68 of the cage, as shown in FIGS. 5-6B, seals off thebottom of the connector 80. The bottom wall 68 is shown as formed from apiece of sheet metal with a bottom plate 72, and side attachment flaps73 that extend along the outer surfaces of the cage sidewalls 64 a, 64b. Openings 74 in the attachment flaps 73 engage catches, or tabs 76which are located on the sidewalls 64 a, 64 b and retain the bottomplate 72 in place. Additional means of attachment may include innerflaps 75 that are also bent up from the bottom plate 68 but arepositioned along the edges of the bottom plate 68 to extend into theinterior hollow space 61 along the inner surfaces of the sidewalls 64 a,64 b. Two such inner flaps 75 are illustrated in FIGS. 1I & 13A andinclude contact tabs 75 a that extend inwardly for contacting oppositesides of an opposing connector inserted into the interior channel 61.Two rims, or flanges 77 a, 77 b, may also be provided at opposite endsof the bottom plate 68 which extend at an angle thereto in order toengage the front and back wall 65 of the cage 63 to make conductivecontact and provide EMI shielding at those locations. The use of abottom wall 68 that covers the entire bottom significantly reduces EMIin this area. Standoffs 69 may be formed in the bottom wall 68 ifdesired. The many points of contact between the bottom wall 68 and thecage 63 provide a reliable EMI shielding gasket along the entire bottomof the connector 80 for the internal connector 70.

Turning now to FIG. 5, the top wall 66 preferably includes an accessopening 81 which communicates with the hollow interior 61 and which isaligned with the internal connector 70 and primarily the area in frontof the internal connector 70. A heat transfer member 82 shown as afinned heat sink may be provided which has a base 84 that extends atleast partially into the access opening 81. The base 84 has a flatbottom contact surface 85 that contacts an opposing surface of a moduleinserted into the cage interior 61. Two retainers 86 are shown as joinedto the top wall 66 and each retainer 86 has a pair of preloaded contactarms 88 that exert a downward retention force on a top plate 87 of theheat sink. An EMI gasket 89 is provided that extends around theperiphery of the opening 81 and is interposed between the top wall 66and the heat transfer member 82.

The connector 80 further includes a rear cover portion 90 that extendsover a rear portion of the interior 61 to cover part of the internalconnector 70. A recess 91 may be formed in the rear cover 90 toaccommodate a chevron-shaped EMI gasket 92 interposed between opposingsurfaces of the rear cover 90 and the top wall 66. The rear cover 90 canbe seen to include an opening in the form of a slot 94. The top wall 66(FIG. 13A) may include an engagement hook 95 as shown that is receivedwithin the slot 94 to engage the top wall 66 to the cage 63 in a mannersuch that the top wall 66 can be slid forward so that its leading edgeabuts the front flange of the connector 80, which may include aprojecting tab 96 formed therewith which engages a corresponding slot 97of the top wall 66. (FIGS. 5A & 13A.) Fastener 99, which may be a screwor other fasteners, may be used to secure the top wall 66 onto the cage63 by engaging threaded holes formed in screw bosses 100 supported bythe cage 63. In this manner, the cage 63 is sealed in a manner tosignificant reduce EMI leakage.

Because the internal connectors 70 are connected directly to the cables60, the connectors 80 need not be mounted to the motherboard 62 bydirect termination, but can be supported by other structures or can beattached by way of fasteners 120 that extend through openings 122 in thecircuit board and into the screw bosses 100. Sealing off of the bottomof the connector 80 and elimination of a right-angle connector not onlyeliminates the need to mount the connector 80 on the motherboard 62 butalso facilitates stacking of the cages/connectors 80 in vertical andhorizontal arrangements. FIGS. 15 & 16 illustrate just two differentstyles of stacking. FIGS. 15 & 15A illustrate a pair of connectors 80with their entrances 67 oriented horizontally in a vertical stack. Thetwo connectors 80 are shown supported on a circuit board 62 by way ofbottom screws 120 that engage the screw bosses 100 in an upward mannerthrough openings in the circuit board. A set of middle screws 124 areprovided to engage the screw bosses 100 of the lower cage and thesescrews 124 have threaded male ends and threaded female ends 126. Thefemale ends 126 engage top screws 99, 128 extending into the screwbosses 100 of the top cage. Thus, multiple connectors 80 may be stackedin such a fashion without requiring complex high speed connecting tracesformed in the circuit board 62 and terminated to the internal connectors70.

FIGS. 16-16A illustrate another manner in which the connectors 80 may bearranged. This arrangement includes a horizontal row of three cages thatare aligned vertically along a front of the host device, but raised offof the circuit board 62. FIG. 15B illustrates a mounting nest 130 thathas a base 132 and two extending sidewalls 133 that form a recess whichaccommodates a connector 80. The mounting nest 130 has two attachmentflanges 134 that can be attached to a faceplate 136 with fasteners asshown extending through openings 135 in the base 132. Fasteners may beused to attach the cages to the nest, and they extend through the baseopenings 135 into the screw bosses 100. The top wall 66 of the connector80 may be attached to the cage 63 with male-female ended fasteners 126as noted above so that adjacent connectors 80 may be assembled into anintegrated arrangement with male fasteners extending through the bases132 of the nests 130 into the female ends 126 of opposing fasteners orinto the screw bosses 100 of the cage. The connectors 80 may also bespaced closely together in instances as shown in FIGS. 14-15B as theheat transfer member 82 has its heat dissipating fins extendingrearwardly of the cage as set forth to follow.

Accordingly, a free-standing connector/cage is provided that can beattached to an external wall of a host device, such as a faceplate orbezel or to a circuit board without requiting any termination tracespositioned underneath the cage. Such a free-standing connector does nothave to be mounted on a circuit board, but may be panel mounted. Theconnector may take the form of an adapter frame, a shielding cage orsimilar type of cage. Still further, the connector may be used an asinternal connecting sleeve to provide an internal connector that ispositioned within the host device and which receives a plug-styleconnector. The connector cables are terminated to the connector elementterminal tails at the proximal ends of the cables, and the cables can beterminated at their distal ends to the chip packages or processors ofthe host device. An integrated bypass assembly such as this can beinstalled and removed or replaced as a unit, which bypasses the circuitboard and the associated loss problems which occur in FR4 materials,thereby simplifying the design and reducing the cost of the circuitboard.

The mating connectors used to connect to the I/O connectors generateheat during operation, and this heat must be removed in order tomaintain efficient transmitting and reception of signals duringoperation. High temperatures can negatively affect the performance ofnot only the modules, but also the devices in which they are used, so itis important to remove this operational heat. Such removal is typicallyaccomplished by the use of heat sinks which include solid bases thatmake contact with selected surfaces of the modules, typically the topsurfaces. These heat sinks further have plurality of heat-dissipatingfins that project upwardly from the bases into the interior space of thedevice. The fins are spaced apart from each other so that air can flowover and around the fins in a manner that heat is dissipated from thefins into the surrounding interior atmosphere. The fins are mountedabove the heat sinks and modules and extend upwardly for a specificheight in order to achieve a desired degree of thermal exchange.However, the use of such heat sinks does not permit a designer to reducethe height of the devices in which modules are used, eliminating thepossibility of reducing the overall heights of such devices.

In this regard, as shown in FIGS. 17-19G, a heat sink assembly 240 isprovided that includes a heat transfer portion 241 which has a solidbase 242 that depends downwardly into the interior space 226 of thecage/connector 222. The heat transfer portion base 242 is complimentaryin shape to the opening 232 in the cage 222 so that the base portion 242may extend through the opening 232 and into the interior space 226 so asto make thermal contact with the top or upper surface of a moduleinserted into the front opening 230 of the interior bay 229 of the cage222. The base 242 may further include a skirt or lip portion 244 thatextends around at least a substantial portion of the periphery of thebase 242, and preferably around the entire periphery of the base 242.This skirt 244 is received in a corresponding recess 246 formed in thetop surface 233 of the cage 222 and which preferably surrounds theopening 232. A conductive EMI ring gasket 247 is provided that fits inthe recess 246 and which encircles the opening 232. The gasket 247 has aplurality of spring fingers 248 that provides a conductive seal betweenthe heat transfer portion skirt 244 and the cage top recess 246 so as toprevent EMI leakage through the opening 232. The EMI gasket 247 sitswithin the recess 246 and surrounds the opening 232 with the springfingers 248 extending radially outwardly, as shown and into contact withthe bottom surface of the skirt 244. The opening 232 in the top of thecage 222 is considered as a contact opening as it permits the heattransfer portion 241 to extend into the interior space 226 of the cage222 and into thermal transfer contact with any module inserted thereinby way of a thermal contact surface 250. (FIG. 19C.)

The heat transfer portion 241 has a solid base portion 242 thatpreferably includes a planar thermal contact surface 250 (on its bottom)that is configured to enter the frame contact opening and contact thetop surface of a module inserted into the bay 229 in effective andreliable thermal contact. The base 242 may include an angled lead-inportion on its contact surface 250 to facilitate the insertion of amodule. The heat sink assembly 240 further includes a distinct heatdissipating portion 252 that dissipates heat generated by the module andtransferred to the heat transfer portion 241 by way of contact betweenthe thermal contact surface 250 and an opposing top surface(s) of themodule. As shown in FIG. 18, this heat dissipating portion 252 isdistinct from the heat transfer portion 241 and is spaced aparttherefrom in a longitudinal or horizontal direction.

The heat dissipating portion 252 includes a base 254 that extends out ina cantilevered fashion from the heat transfer portion 241 along asimilar longitudinal axis. A plurality of vertical heat-dissipating fins256 are disposed on the base 254 and extend vertically downwardly fromthe heat dissipating portion base 254. As illustrated, the fins 256 arespaced apart from each other in the longitudinal (horizontal) directionto define a plurality of cooling passages 258 therebetween that arespaced away lengthwise from the heat transfer portion 241 and whichfurther extend lengthwise with respect to the modules. In order toretain the heat transfer portion 241 in contact with a correspondingmodule, and also resist any moment that may occur due to the weightand/or length of the heat dissipating portion 252, retainers 260 areillustrated. These retainers 260 are attached to the frame top surface233 by means of fasteners, such as rivets 262, which may be formed aspart of the cage 222 in the nature of vertical posts 263 that arereceived within corresponding openings 264 disposed in the retainer baseportion 265. The free ends of these posts 263 may be “dead-headed” or“mushroomed” to form the connection between the retainers 260 and theskirt 244. The retainers 260 are seen to have pairs of cantileveredspring arms 267 associated with them and which extend longitudinallyfrom the base portions 265 as illustrated. The spring arms 267 areflexible and are formed as elastic spring arms 267 with a preformeddownward bias. The spring arms 267 terminate in free ends 268 and theyextend at a downward angle into contact with the heat transfer memberskirt 244. Four such contact points are provided for the heat sink 240assembly illustrated in the Figures, and the contact points will definea four-sided figure when connected by imaginary lines. However, thecontact points of the spring arms 267 may vary from the locations shownaccording to the extent to which space is available on the skirt portion244 of the heat sink member 240.

The elasticity of the spring arms 267 permits a designer to obtain adesired contact pressure by configuring the length of the spring arm267, the depth to which the spring arm 267 depends down into the recess246 and the height of the stub 269 that joins the spring arm 267 to theretainer 260. The fastener connection of the retainer 260 to the skirtplate 244 eliminates forming and utilizing attachments on the sides ofthe cage 222 which would take up space and affect spacing between cage222. The rivets 262 also have a low profile so that the frame 226 is notunduly enlarged in any direction, including the vertical direction. Thespring arms 267 are relatively short in length and therefore contact theheat transfer portion 241 at approximately four corners thereof to exerta reliable contact pressure on it in order to maintain it in goodthermal transfer contact with any modules.

Uniquely, the heat-dissipating fins 256 are removed from immediatecontact with the heat transfer portion 241 of the heat sink assembly240. Rather, they are positioned on the heat dissipating portion 252 andthey extend downwardly therefrom. The fins 256 are longitudinally spacedaway from the heat transfer portion 41 and its base 242. The fins 256are further arranged in a series of planes, shown as vertical planes F,that intersect both the horizontal plane, H1, in which the heat transferportion skirt extends and the horizontal plane H2 in which the thermalcontact surface(s) 250 extend. As shown in FIG. 19C, not only do thevertical planes F intersect the two planes H1 and H2, but the finsthemselves extend for heights that intersect those two planes.Furthermore, adjacent fins 256 are separated by intervening coolingpassages or air channels through which air may circulate. The fins 256and cooling passages 258 extend transversely to a longitudinal axis ofthe heat sink assembly 240. In this manner, the fins 256 may occupy thespace R rearwardly of the cage 222 and above the wires 272 which areterminated to the receptacle connector 271 supported in the cage 222.Locating the fins 256 in this manner permits the overall height of thedevice in which the cage strictures are used to be reduced byapproximately the height of the fins that ordinarily would projectupwardly from the cage. It is desired to have the fins 256 not touch thewires 272 in this orientation. In this regard, the height of the fins256 is preferably less that the height of the cage 222 as illustrated inthe Figures.

The heat transfer and heat dissipating portions 241, 252 are shown asbeing integrally formed as one piece to promote heat transfer from thetransfer portion 241 to the dissipating portion 252. However, it iscontemplated that the two portions 241, 252 could be formed separatelyand subsequently joined together where desirable. In order to furtherenhance the transfer of heat from the heat transfer portion 241, athermal transfer member 274 is provided that extends lengthwise alongand in contact with the heat transfer and heat dissipating portions 241,252. Such a transfer member 274 is shown in the Figures as a heat pipe275, having an oblong, or elliptical, cross-sectional configurationwhich include major and minor axes that define such a shape. (FIG. 19D.)The oblong configuration of the heat pipe 275 increases the amount ofcontact area between the heat pipe 275 and the two portions 241, 252 ofthe heat sink assembly 240. Other non-circular configurations such as arectangular inner cavity may be utilized or even cylindrical ones. Theheat pipe 275 is received within a common channel 278 that also extendslongitudinally along the heat sink assembly 240 and it follows thecontour of the two portion 241, 252. Accordingly, the heat pipe 275 hasan offset configuration with two distinct portions 279, 280 that extendat the different heights, or elevations, of the heat sink assembly 240.

The heat pipe 275 is a hollow member with an inner cavity 282 defined bysidewalls 283 that is sealed at its ends and which contains a two-phase(e.g., vaporizable) fluid within its inner cavity 282. Examples of atwo-phase fluid that can reside within embodiments of inner cavity 282include purified water, freon, etc. The heat pipe 275 and its walls 283can be composed of aluminum, copper or other thermally conductivematerials. The inner cavity 282 preferably includes an evaporator region279 located adjacent the heat transfer portion 241 and a condenserregion 280 located adjacent the heat-dissipating portion 252. Heat istransmitted from the heat transfer portion 241 through bottom and sidewalls 283 of the heat pipe 275 into the inner cavity 282 where is cancause the two-phase fluid present in the evaporator region 279 toevaporate. This vapor can then be condensed to liquid in the condenserregion 280. In the illustrated embodiment, the vapor gives up heat as itcondenses, and that heat is transmitted out of the inner cavity 282through the walls 283 of the heat pipe 275 into the base of the heatdissipating portion 252 and its associated fins 256. The inner cavity282 may include a wick 284 to facilitate travel of the condensed liquidalong the wick back to the evaporator region 280. (FIG. 19D.) The wick284 may take the form of grooved channels on the interior surface of theinner cavity 282, or an extent of wire mesh or the like.

As illustrated, the heat transfer and heat dissipating portions 241, 252of the heat sink assembly 240 extend longitudinally but extend atdifferent elevations, with the heat dissipating portion 252 being raisedwith respect to the heat transfer portion 241. This difference inelevation facilitates, to some extent, the movement of the liquid vaporfrom the heat transfer portion 241 up into the heat dissipating portion252, but its primary purpose is to accommodate the heat dissipatingportion 252 in its horizontal extent without having to modify the frame222 to accommodate it. If one desired to extend the heat dissipatingportion 252 at the same elevation as the heat transfer portion 241, therear wall 224 and a portion of the top surface 233, proximate theretowould need to be modified. A channel, or recess, may be formed in thosetwo walls 224, 233 to accommodate the area of the heat sink assembly 40between the heat transfer and dissipating portions 241, 252. Also,although mostly one heat pipe 275 has been discussed, it is understoodthat multiple heat pipes, such as a pair of heat pipes 290, asillustrated in phantom in FIG. 19E may be routed in the heat sinkassembly channel. In this instance, the pair of pipes may beencapsulated in a medium that facilitates heat transfer to make up forthe amount of direct contact lost between a pair of heat pipes and asingle, oblong configured heat pipe as illustrated. Thermally conductivegreases or other compounds may be applied to the heat pipes to enhancethe thermal transfer.

This heat sink assembly thermally engages the cage and uniquelytransfers heat therefrom to an area rearwardly of the cage. With thisstructure and its downwardly depending heat dissipating fins, thedevices in which such heat sink assemblies are used can have a reducedheight, permitting additional devices in closets and stacks. Thelocation of heat dissipating tins is such that all of the spaces betweenthe fins are used for cooling as none of them have light pipes or anyother members extending therethrough. The heat sink heat-dissipatingportion extend horizontally but spaced above the motherboard of thedevice so a designer can utilize this open space for additionalfunctional components without increasing the lateral size and depth ofthe host device. Examples of the manner in which the connectors with theheat sinks integrated therewith can be arranged and mounted for use in ahost device are illustrated in FIGS. 15-16A.

As noted above, the cage of the connector 80 can be formed in a mannerthat allows for positioning the connector 80 in manner where theconnector 80 is not supported by a circuit board and instead can besupported by other structures (such as conductive or insulative frames).In such a configuration, all the terminals are preferably connected toconductors in a cable so that signals (high speed and low speed) can bedirected appropriately. In many such embodiments, the cage of theconnector may be formed using a die cast material. Such a constructionis not required as convention stamped metal construction will also besuitable.

While a cage can be supported by a separate structure such as a frame,it should be noted that the connector can be mounted to a circuit boardin a more conventional manner. For example, connector 80′ in FIG. 20 isformed of stamped material and is configured to be press fit into acircuit board and provides multiple ports 80 a′ in a gangedconfiguration. The cage 63′ includes dividing walls 63 a′ that helpdefine the ports and the cage 63′ includes tails 63 b′ that areconfigured to be pressed into a circuit board. For certain systemconfigurations where extending a circuit board to an edge of the box isdesired, it may be beneficial to have the connector 80′ configured sothat it can be mounted on the circuit board in a press-fit fashion asshown. In such a configuration, the high speed signal terminals areexpected to be connector to cables but the low speed signals can bemounted to cables or connected to the circuit board in a desirablemanner (for example, a connector such as is depicted in PCT ApplicationNo. PCT/US2014/054100, which is incorporated herein by reference in itsentirety).

FIG. 21 illustrates an embodiment of a computing device 300. The device300 includes a chassis 301 with a first wall 305 a and a second wall 305b. As depicted, the first wall 305 a in a front wall and the second wall305 b is a rear wall (thus the first and second walls 305 a, 305 b areopposing) but the first and second walls 305 a, 305 b do not need to beon opposing sides and thus a number of configurations are possible.

The chassis 301 supports a main circuit board 312 that extends toadjacent the front wall 305 a. A chip package 340 is provided on thecircuit board 312 and first connectors 321 are connected to the chippackage 340 by cables 322 that carry the high speed signals. A secondconnector 331 is positioned at the second wall 305 b and is connected tothe chip package 340 by cables 332. Power is provided to the circuitboard 312 (and the various components supported thereby) via powerconnection 330. It should be noted that the distance between the firstand second walls 305 a, 305 b can exceed 20 inches and thus would beproblematic if the circuit boards were to be used to transmit the highspeed signals, especially as the data rate approaches and exceeds 25Gbps. Using non-return to zero (NRZ) encoding would require a signalingfrequency of about 12.5 GHz and such frequencies are poorly compatiblewith conventional FR4 based circuit boards. In addition, as data ratesapproach 40 Gbps (and the signaling approaches 20 GHz) even the use ofexotic materials would likely be insufficient to allow for conventioncircuit board techniques to be used.

FIGS. 22-27 illustrate another embodiment of a computing device.Specifically, computing device 400 includes a chassis 401 with a firstwall 405 a and a second wall 405 b. A main circuit board 406 is providedand the main circuit board includes component circuitry 407. Componentcircuitry 407 can include power supplies, cooling fans and variousdigital signaling chips that either do not need to operate at highfrequencies in order to support desired bandwidth or are intended totravel short distances. A support connection 408 (which is shown as acable assembly for ease of assembly but could also be a two boardconnectors) can provide control signals and/or power signals to a signalboard 410 that supports one or more chip packages 440.

First connectors 421 are positioned along the first wall 405 a so as toprovide ports 421 a in the first wall 405 a. Similarly, secondconnectors 431 are positioned along the second wall 405 b so as todefine an appropriate mating interface along the second wall 405 b. Ascan be appreciated, however, the signal board 410 does not extend tofirst or second connectors. Instead, the first connectors 421 arecoupled to the chip package 440 via cables 422 while the secondconnectors 431 are coupled to the chip package 440 via cables 432. Thefirst connectors 421 can be formed in a manner similar to that which wasdiscussed above and thus the internal details of connector 421 will notbe repeated here for purposes of brevity. Instead it will just be notedthat the above features of such a connector can be used herein in adesired manner and in a desired combination so as to provide a connectorthat meets the system requirements.

As can be appreciated, the first connectors 421 could be supported by afront circuit board 411. Alternatively, the front circuit board could beomitted and a frame such as frame 132 (discussed above) could be used tosupport the first connectors 421. If the front circuit board 411 is usedthen connector supports 411 a can be used to secure the first connector421 to the front circuit board 411.

The signal board 410 supports the chip package 440, which includes achip 445, and arranged around the chip package 440 are a plurality ofsignal board connectors 426. Traces, as discussed above, can connect thechip 445 to the signal board connector(s) 426 and, as discussed above,an optional substrate can act as a connection between the chip 445 andthe signal board 410. In an embodiment, such as is depicted in FIG. 27,the signal board connectors 426 can be positioned on at least two sidesof the chip 445 and potentially can be positioned on four sides so as toincrease system capacity. If desired, at least two signal boardconnectors 426 can be provided on each side of the chip 445. Naturally,further increases in density can be provided if the signal board 410 (orcorresponding structure if a signal board is not used) has a chip onboth sides (e.g., on top and bottom).

In operation it is expected that the signal board 410 will be prepared(which may include passing through a solder reflow operation) and thenbe mated to the first connector 421. To allow for such an installationprocess, the cable 422 has a first end 422 a terminated to the firstconnector 421 and a second end 422 b is terminated to first boardconnectors 423 and first board connectors 423 are mateable with thesignal board connectors 426. Likewise, cable 432 can have a first end432 a terminated to the second connector 431 and a second end 432 bterminated to the second board connectors 433. Such a configurationallows the signal board 410 to be mounted in the chassis 401 beforebeing connected to the first connectors 421 and second connectors 433.In operation, it is expected that signal board connector 426 willinclude a housing 426 a that supports a plurality of terminals 429 thatare soldered to the signal board 410. Of course, in alternativeembodiments a signal board connector could be press-fit onto the signalcircuit board 410. As the use of solder or press-fit to mount aconnector on a circuit board is well known, no further discussion ofsuch connector details will be provided herein.

Regardless of how the signal board connector 426 is mounted on thesignal connector board 410, it provides a mateable interface to thesignal connector board 410. The signal connector board supports a chip445 (which typically will be on a carrier or substrate of some nature).The chip 445 can be connected to the signal circuit board 410 asdiscussed above and can be supported by a thermal frame 442 thatsupports a cooling block 441. The cooling block 441, which can be in theform of a conventional heat sink, includes a cooling base 441 a thatwill preferably be compressed against the chip 445 and may includecooling fins 441 b to increase surface area and improve cooling of thechip. As can be appreciated, a thermal transfer compound 443 willthermally couple the chip 445 to the cooling base 441 a.

The chip 445, which as discussed above can be an ASIC, DSP and/or anydesired combination of controllers and processors, thus is connected tothe first connector 421 and the second connector 431 via only a veryshort path through a signal circuit board 410. As signal loss is relatedto the distance traveled along the board, shortening the distance asdepicted allows for much lower loss than convention systems whileallowing for the use of conventional circuit board materials andconstructions methods.

FIGS. 28A and 28B illustrate an alternative embodiment of a signal boardconnector and first board connector. Specifically, a first boardconnector 523 includes a housing 523 a that supports one or more rows ofcables 522. The housing 523 a of the first board connector 523 mateswith a signal board connector 526 that includes a housing 527 a in acage 527 b that has legs 527 c that, in operation, help secure the cage527 b to the corresponding signal circuit board. A biasing member 528 asecures the first board connector 523 in the signal board connector 526and includes an actuation member 528 b that, when actuated, allows thefirst board connector 523 to be removed from the signal board connector526.

Naturally, other configurations of the first board connector and signalboard connector are possible and thus the depicted embodiments are notintended to be limiting unless otherwise noted. In addition, the firstboard connector and the second board connector may be the same or can bedifferent so as to ensure that the proper connectors cannot be mountedin the wrong location. To further protect from potential installationproblems, each of the first board connectors and second board connectorscan be keyed differently so that only the desired configuration can beinstalled.

FIG. 29 illustrates an alternative embodiment of a chip package 640. Asupport layer 614 is provided that supports a flex layer 690, that inturn is supporting a substrate 646 and the substrate 646 supports a chip645. The chip 645 and substrate 646 can be as described above. Thesupport layer 614 could be a circuit board or some other material. Whilethe support layer 614 is shown as being relatively comparable in size tothe chip 645 and the substrate 646, in practice it is expected that thesupport layer will be larger than the chip 646 and the substrate 646 soas to provide additional support. As can be appreciated, rather than usea circuit board to couple the chip to a connector, the depictedembodiment uses a flex circuit to couple connectors 626 to the chip 645.The entire chip package 640 can be supported by a frame (not shown) orby the support layer 614, depending on the desired configuration and caninclude heat sinks to help dissipate heat away from the chip. In such asystem the support layer 614 could provide a mounting point for the heatsink similar to that discussed above.

Flex circuits can be made with an intricate pattern as they can bemultiple layers thick and the flex circuit 690 can terminate to multiplesignal board connectors 626 (which would be configured to be connectedto corresponding first board connectors so that the rest of the systemwas substantially the same). Thus, solder connections between the flexcircuit 690 and the substrate 646 or chip 645 are possible. And, as canbe appreciated, a flex circuit can provide high performance, relative toa circuit board. It should be noted that while the substrate 646 isdepicted as a separate component, in an embodiment the flex circuit 690could replace the substrate 646 and thus the use of the substrate 646 isoptional in the chip package 640. As can be appreciated, therefore, asignal board connector can but does not have to be mounted on a circuitboard.

It should also be noted that the flex circuit, which often is formedwith KAPTON but can also be a rigid-flex circuit, can be formed withpolyimide, acrylic adhesive, epoxy adhesive and fluoropolymer adhesivesolutions. Thus the choice of material is not intended to be limiting asthe design of the system allows even relatively lossy materials like FR4to be used effectively.

Specifically, the path lengths of traces in the signal board (if asignal board is used) are kept short such that for frequencies around 15GHz (which is slightly above to what is needed to support 25 Gbps usingNRZ encoding and 50 Gbps using PAW encoding) it is expected that lessthan 2 dB (preferably less than 1 dB) of insertion loss due to thecircuit board can be provided between the chip and the signal boardconnector. This is because even less expensive circuit board materialscan provide less than 1 dB of loss per inch of travel at that frequencyand the system design allows the traces to have a relatively short pathlength (often less than two inches long) between the chip and the signalboard connector. Higher performance circuit board materials can provideloss in the range of about 0.5 dB per inch. Thus it is feasible to haveless than 1 dB of loss between the chip and the signal board connector.Naturally, as the operation frequency increase and approaches 25 GHz thedepicted configurations that allow for reducing insertion loss becomeeven more important. Applicants have determined that even for 25 GHzsignaling operation the depicted system can still provide relatively lowinsertion loss (less than 2 dB of insertion loss in the circuit boardfor well-designed systems) and thus the depicted configurations may behighly desirable for high performance applications. In addition, formore sensitive applications a conventional circuit board can be omittedand the chip can be connected to a flex circuit that is terminated tothe signal board connector so as to potentially provide less insertionloss than is typically found with circuit boards.

The disclosure provided herein describes features in terms of preferredand exemplary embodiments thereof. Numerous other embodiments,modifications and variations within the scope and spirit of the appendedclaims will occur to persons of ordinary skill in the art from a reviewof this disclosure.

We claim:
 1. A computing device, comprising: an enclosure with a firstwall; a chip package including a chip electrically connected to a firstsignal board connector; a first connector supported near the first wall,the first connector including a cage and an internal connector with amating interface, the internal connector supporting a first pair ofterminals, each terminal of the first pair of terminals having a contactin the mating interface, the first connector being supported above acircuit board; a first cable with a pair of conductors, the cableincluding a first end and a second end, a first end of the cableterminated to the first pair of terminals; a first board connector, thefirst board connector terminated to the second end of the first cableand configured to mate with the first signal board connector; andcomponent circuitry that provides power to the chip.
 2. The computingdevice of claim 1, wherein the chip is supported by a signal board andthe first signal board connector is mounted on the signal board.
 3. Thecomputing device of claim 2, wherein the enclosure includes a secondwall, the computing device including a second connector supported nearthe second wall, the second connector terminated to a first end of asecond cable, the second cable having a second end terminated to asecond board connector, wherein the signal circuit board supports asecond signal board connector that is electrically connected to thechip, the second board connector configured to mate with the secondsignal board connector.
 4. The computing device of claim 2, wherein thecomponent circuitry is connected to the signal board via a cableassembly.
 5. The computing device of claim 1, wherein the chip packageincludes a substrate that supports the chip.
 6. The computing device ofclaim 5, wherein the substrate is supported by a signal board, thesignal board not extending to the first connector.
 7. The computingdevice of claim 6, wherein the first connector is supported by a nest,the nest being supported in a cantilevered fashion from the first wall.8. The computing device of claim 1, wherein the chip is electricallyconnected to a plurality of signal board connectors and each of theplurality of signal board connectors are mated to a different firstconnector via a corresponding board connector.
 9. A connector system,comprising: a first connector including a cage and an internal connectorsupported by the cage, the internal connector including a card slot witha plurality of terminals positioned on two sides of the card slot, theplurality of terminals each including contacts that extend into the cardslot and tail portions, the cage opening being orientated in a verticalalignment; a plurality of cables, each of the cable with a first end anda second end, the first ends being terminated to the tail portions; afirst board connector terminated to the second ends of the plurality ofcables; a signal board supporting a chip, the signal board having tracesconnected to the chip; and a signal board connector mounted on thesignal board, the signal board connector including terminals that areelectrically connected to the traces, the signal board connectorconfigured to mate with the first board connector.
 10. The connectorsystem of claim 9, wherein the signal board connector is a first signalboard connector and a second signal board connector is mounted on thesignal board, the first and second signal board connectors beingpositioned on two sides of the chip.
 11. The connector system of claim9, wherein the signal board connector is one of a plurality of signalboard connectors and at least of the plurality of signal boardconnectors is mounted on each of four sides of the chip.
 12. Theconnector system of claim 9, wherein the insertion loss in the signalboard is less than 2 dB when operating at 15 GHz.
 13. The connectorsystem of claim 9, wherein the insertion loss in the signal board isless than 1 dB when operating at 15 GHz.
 14. The connector system ofclaim 9, wherein the insertion loss between the chip and the signalboard connector is less than 2 dB when operating at 15 GHz.
 15. Theconnector system of claim 8, wherein the plurality of signal boardconnectors are arranged on a plurality of sides of the chip package. 16.The connector system of claim 15, wherein the plurality of signal boardconnectors are arranged on four sides of the chip package.
 17. Theconnector system of claim 9, further comprising a thermal transferportion that is positioned on top of the cage, the thermal transferportion including a heat pipe that is configured to direct thermalenergy from inside the cage to a location rearward of the cage.
 18. Theconnector system of claim 1 further comprising a thermal transferportion that is positioned in the cage, the thermal transfer portionincluding a heat pipe that is configured to direct thermal energy frominside the cage to a location rearward of the cage.
 19. The connectorsystem of claim 18, wherein the thermal transfer portion has a pluralityof fins arranged rearward of the cage, the plurality of fins configuredto act as a heat sink.
 20. A computing device, comprising: an enclosurewith a first wall; a chip package including a chip electricallyconnected to a plurality of signal board connector; a plurality of firstconnectors supported near the first wall, each of the first connectorsincluding a cage and an internal connector with a mating interface, eachof the internal connectors supporting a first pair of terminals, eachterminal of the first pair of terminals having a contact in the matinginterface; a plurality of cables, each of the cables having a pair ofconductors and a first end and a second end, the first end of each ofthe cables terminated to a respective one of the first pair ofterminals; a plurality of board connector, the board connectorsterminated to the second ends of the plurality of cable and configuredto mate with first signal board connectors, wherein the plurality ofsignal board connectors are arranged on at least two sides of the chippackage.
 21. The computing device of claim 20, wherein the plurality ofsignal board connectors are arranged on two opposing sides of the chippackage.
 22. The computing device of claim 20, wherein the plurality ofsignal board connectors are arranged on three sides of the chip package.